Update docs/reference/service.md

Co-authored-by: Julian Alberts <julian.alberts@contact-software.com>

Author: jens-kuerten

docs/reference/service.md

@@ -50,7 +50,7 @@ The `service.file_upload` object allows you to upload new files to the CIM Datab
 ### Upload a new file
 
 ```python
-service.upload_new_file(
+service.file_upload.upload_new_file(
         self,
         parent_object_id: str,
         filename: str,